Imaging technologies incorporating penetrating radiation such as x-rays or gamma rays have found widespread use in applications as diverse as medical imaging and cargo inspection. X-ray imaging techniques involve aiming a beam of the radiation at an object to be imaged and measuring the intensity of x-rays received through the object. The attenuation of the x-ray beam depends on material properties of the object such as mass density or effective atomic number. By acquiring such attenuation data over a range of paths through the object, it is possible to reconstruct a three-dimensional or projected two-dimensional image of the object.
In security applications, the three-dimensional volumetric or two-dimensional projection images can be used to detect suspicious or dangerous objects hidden in baggage or cargo, for example, contraband.